Hi, All. I need to connect an array of panels to the Isolator/Surge Db which will be in the inverter-room.

The ground-mounted panels are about 80 meters away.

Is it acceptable to use SWA ECC cable for the underground run ?

Also - It would be great if I could run 2 strings on one 4-core cable.

Also - what size would you-all recommend, in sq mm

Cheers, Charles

If the array is high voltage in series (250v+) then 6mm² should be ok, that is quite a long run so ideally 8mm² would be safer with less voltage drop.
As for the type of cable, and using 4 core, some of the more clever guys here on the forum can answer that :)

Thanks. The array Voc is 905v, Isc is 28A - (MPPT range is 200~1000v)

I am thinking 10mm 4-core to carry both arrays (18 panels per string, 2 strings in parallel per array)

Cheers

3 hours ago, CharlieD said:

Thanks. The array Voc is 905v, Isc is 28A - (MPPT range is 200~1000v)

I am thinking 10mm 4-core to carry both arrays (18 panels per string, 2 strings in parallel per array)

Cheers

I am skeptical of using a single 4 core cable. Fault finding might be more challenging, higher fault level also but the main thing is, will you be able to COC that. I am unsure if that will be compliant. The last point is your main concern. I personally would do 2 separate 2 core cables. Also that Isc is a bit high, I have never seen a panel over 19A. Which brand of panels is this. A 6mm2 cable over that distance will work more than fine as the voltage drop is less than 2% at that current. If the Imp current is less than 20A which i am pretty sure it is, then the voltage drop will be less than 1%.

Never mind, i saw the parallel comment

Edited August 4, 2025Aug 4 by Denns

Just remember that most 4 core armoured cable you find will be rated at 600V. You are probably going to pay through your teeth for cable rated at 1000V.

I would use proper solar cables rated at 1500 volts. I would run it in a large conduit

6mm wire should be fine , about 1.6% volt drop

On 2025/08/05 at 10:59 AM, JustinSchoeman said:

Just remember that most 4 core armoured cable you find will be rated at 600V. You are probably going to pay through your teeth for cable rated at 1000V.

Is the 600V not the RMS AC value and the maximum peak value 1000V for the common armoured cable 600/1000V?

21 minutes ago, Scorp007 said:

Is the 600V not the RMS AC value and the maximum peak value 1000V for the common armoured cable 600/1000V?

No

It is 1000 volt wire to wire (both have their own insulation) and 600 volt wire to earth

Although there is still another layer of plastic before the armouring

1 hour ago, Scorp007 said:

Is the 600V not the RMS AC value and the maximum peak value 1000V for the common armoured cable 600/1000V?

AC cables are tested and rated for AC conditions. Unless the manufacturer tests for DC conditions, you would be hoping for insulation material that can cope with DC.

for interest sake, I just had a look at my roll of helukable solarfelx pv.

its rating is 1500v DC and 1000v AC for 2.5mm2 up to 240mm2

cable spec sheet states that it can be used underground

hanks everyone for your responses.

I have decided to run 2+ve RED and 2-ve Black solar wires in a pvc pipe. 6mm

Since the panels and their concreted-in Galv steel frame will be well earthed (With CCS spikes too), There will be fusing and surge arrestors at both ends of the 80 meter run, there is no need for a separate earth wire between panels and inverter - right ?

23 minutes ago, CharlieD said:

hanks everyone for your responses.

I have decided to run 2+ve RED and 2-ve Black solar wires in a pvc pipe. 6mm

Since the panels and their concreted-in Galv steel frame will be well earthed (With CCS spikes too), There will be fusing and surge arrestors at both ends of the 80 meter run, there is no need for a separate earth wire between panels and inverter - right ?

In theory, you should have one common earth

The earth at your main DB should be the same everywhere

The only way to get this is to run an earth wire. On such a size installation, an extra roll of earth wire will be a small cost

Just remember that solar wire can be difficult to pull through a conduit

Make sure you use an oversized conduit

54 minutes ago, James 1 said:

In theory, you should have one common earth

The earth at your main DB should be the same everywhere

The only way to get this is to run an earth wire. On such a size installation, an extra roll of earth wire will be a small cost

Just remember that solar wire can be difficult to pull through a conduit

Make sure you use an oversized conduit

Yup, I see your point, but it just seems pointless since the structure is freestanding, and 80 meters from the building. Will put one in anyway - as you say, in the greater scheme of things, it is small cost.

For pulling wiring through - I use a domestic vacuum cleaner to suck a cotton wad and nylon line through, then use that to pull the wiring

Some brands of solar wire tend to "stick" to the conduit more than others

Can be a problem even on short runs l

1 hour ago, James 1 said:

Some brands of solar wire tend to "stick" to the conduit more than others

Can be a problem even on short runs l

That's what they made Baby Powder for !

Fish tape.

Pull boxes.

4 hours ago, Virwat said:

Fish tape.

Pull boxes.

Good point. The regulation clearly states after? degrees of bends there must be a pull box.

13 hours ago, stefan44 said:

for interest sake, I just had a look at my roll of helukable solarfelx pv.

its rating is 1500v DC and 1000v AC for 2.5mm2 up to 240mm2

cable spec sheet states that it can be used underground

Thanks for the actual specs. This comes back to the RMS AC and peak value mentioned.

1 hour ago, Scorp007 said:

Thanks for the actual specs. This comes back to the RMS AC and peak value mentioned.

True for insulation that can take it. However, on Medium Voltage, you are not supposed to test XLPE cables with DC.

I’ve worked with gear that needed the same kind of step‑by‑step production flow, and having everything synced makes a huge difference. Checking out electric cable options from this supplier helped me figure out which machine setups actually cut downtime and which ones were just overkill. Their ability to tweak configurations based on what you’re trying to make saved me a lot of guesswork.

Edited February 20Feb 20 by Bubblerate

In the case of Hv pv strings i use Armadac SWA rated for max 3.3kv. I use these armoured cable on the solar farm upgrade in LA Réunion. Just ensure to place your order well in advance as their might be a delivery time line.

Voltex

Sorry embedded link not working let me try the link.

https://www.voltex.co.za/product/armadac-10.00mm-copper-pvc-pvc-swa-pvc-fire-retardant-1.9-or-3.3kv-black-or-red?srsltid=AfmBOop-_FX5-a9t81L5hkMf4cQkhQTAP6r_QOQAmlJq42s0iqpUDu4L

Edited February 18Feb 18 by TaliaB

6 hours ago, TaliaB said:

Sorry embedded link not working let me try the link.

https://www.voltex.co.za/product/armadac-10.00mm-copper-pvc-pvc-swa-pvc-fire-retardant-1.9-or-3.3kv-black-or-red?srsltid=AfmBOop-_FX5-a9t81L5hkMf4cQkhQTAP6r_QOQAmlJq42s0iqpUDu4L

Great idea, thanks. I have used this same Armadac for transformer-to-transformer connections in irrigation systems, at 3.3kV ... not difficult to get, though most suppliers like to sell 500m drums on